In the spring of 589 BCE, Duke Qing of Qi invaded the northern borders of Lu, seizing vast lands. Wei sent troops to aid Lu but suffered defeat. Both states turned to Jin for help, and Duke Jing of Jin dispatched his general Xi Ke with 800 chariots to their rescue.
However, Duke Qing of Qi, intoxicated by his victories, completely dismissed the allied forces of Jin and Lu. When the two armies met at An, the duke, eager for a quick triumph, sent a messenger to the Jin camp with a challenge, proposing a decisive battle at dawn the next day.
The next morning, the two armies formed their battle lines. Duke Qing of Qi, brimming with confidence, personally beat the war drum and commanded his troops to charge, shouting loudly, "Warriors of Qi, charge! Let us first destroy the enemy before us, then enjoy a delicious breakfast!"
The first wave of the Qi army's assault was ferocious, their chariots surging like a tidal wave and arrows raining down on the Jin forces. The Jin commander Xi Ke was struck in the arm by an arrow, blood gushing forth, yet he continued beating the war drum to direct the battle. His charioteer Xie Zhang, himself wounded by an arrow, took the drumsticks from Xi Ke's hand and pounded the drum with all his might, rallying the Jin troops to charge forward with renewed vigor.
Under the fierce assault of the Jin army, the Qi forces began to waver, their formation crumbling. The Jin soldiers, emboldened, pressed their attack, and the Qi troops scattered in defeat. Duke Qing of Qi, shielded by his charioteer Bing Xia, barely managed to escape the chaos.
Duke Qing of Qi, arrogant and contemptuous of his enemy, boasted he would "destroy them before breakfast," only to suffer a crushing defeat before he could return to camp. Later, people used the idiom "destroy them before breakfast" to describe resolute determination and eagerness to annihilate the enemy.
Source: *Zuo Zhuan*, "Duke Cheng's Second Year"
Meaning of the Idiom: Later, the Chinese idiom "灭此朝食" came to describe how resolute determination and eagerness to annihilate the enemy.